In the construction of a gas burner assembly for a gas range or stove, the gas is commonly supplied to ach burner unit of the range through a manifold constructed of upper and lower sheet metal panels. The panels are coupled together and define gas supply passages extending to annular gas chambers each defined between concentric openings within the upper and lower walls of the manifold. A gas burner unit projects upwardly from each set of concentric openings and includes inner and outer generally cylindrical sheet metal walls defining an annular chamber which connects with the corresponding annular chamber within the manifold. The outer wall is provided with small circumferentially spaced openings through which the gas escapes for ignition by a pilot light or a spark igniter.
The inner wall of each burner unit includes a reduced cylindrical portion projecting downwardly from an annular shoulder within the unit and into the opening within the bottom wall of the manifold. Commonly, each burner unit is secured to the manifold by an aluminum fitting having a flange portion engaging the shoulder and projecting outwardly from a downwardly projecting tubular portion having externally cut fine helical threads. The aluminum fitting has a relatively thick wall thickness so that the fine helical threads may be cut into the fitting without substantially weakening the fitting. The helical cut threads receive a cast metal or aluminum nut having internally tapped or cut fine threads which mate with the cut threads on the tubular fitting.
It is desirable for the attachment fitting and nut to be of substantial diameter with the fitting having an open bottom so that any liquid which accidentally spills into the burner unit will flow downwardly through the burner unit and fitting and into a drip pan below the manifold. The relatively large size of the tubular fitting and cast nut and the substantial metal required to form the fitting and nut result in adding a significant cost to secure each gas burner to the manifold. The fine threads of the fitting and nut sometimes present a problem of cross-threading of the nut onto the fitting, and this results in scrapping the fitting and nut.